MORE than 130 fires are still raging across NSW as thousands of firefighters remain on standby in the face of some of the worst fire conditions in the state's history.

With temperatures in Sydney hovering near 43C - only the third time that mark has been hit since records were first kept 150 years ago - and severe dry and hot Westerly winds of up to 40km/h creating furnace-like conditions for NSW and parts of Victoria, fire crews and emergency authorities are bracing for the worst.

40 fires remain uncontained at 4pm, with firefighters pinning their hopes on a late, but slow-moving southerly coming through later tonight to help cool conditions.

We'll keep you updated with the latest news, photos, and videos throughout the day.

8.30pm The RFS is reporting a home has been lost at Jugiong, north east of Gundagai. The property was consumed by fire near the intersection of Cobbler Road and the Hume Highway. A spokeswoman for the RFS said 20 more homes in the area are now under threat.

5.16pm The fire at Deans Gap in the Shoalhaven is moving easterly towards the Princes Highway. An alert has been sent out to the people of Wandandian. 13 trucks, 60 firefighters and 3 aircraft are battling the 15 hectare blaze.

The fire at Tarcutta is still posing a threat but the degree has lessened since earlier. 23 trucks, 66 firefighters and 2 aircraft are battling the 560 hectare blaze. Residents are advised to take shelter.

The threat to Kybeyan Valley near Cooma has passed with no property under threat. 14 trucks and nine aircraft are battling the 4500 hectare blaze.

4.45pm Dozens of homes are under threat as NSW firefighters battle 135 blazes in 40-plus temperatures and "catastrophic" conditions.

The worst fires are in the south of the state, near Cooma, Nowra, Bega and Wagga.

But although 40 remained uncontained, there had been no reports of loss of life or homes as residents heeded dire warnings from authorities.

"We have been very fortunate," said Rural Fire Services (RFS) Commissioner Shane Fitzsimmons, who praised the "extraordinary" firefighting effort taking place in "dirty, hot difficult conditions".

Hundreds of firefighters were in the field, with thousands more on standby, as temperatures climbed and the fires, fanned by winds over 70 km/h, burned more than 26,000 hectares of grass, scrub and bushland.

Thirty homes were threatened by a fire 12km east of Cooma - 20 in the Kybeyan Valley and 10 around Mount Forest Road in the Cooma-Monaro area.

A fire on the south coast at Brogo, near Bega, was expected to affect isolated properties north of Eagles Nest Road.

There has been some respite in the Bega area, after temperatures eased to the mid-20s following a southerly wind change just after 2pm.

An emergency bushfire warning was issued for the township of Tarcutta, in southwest NSW, where the fire front was about 3km from properties shortly before 1pm.

Other fires at an "emergency" alert level were at Oura, Mates Gully and Munyabla, near Wagga, and Narrandera, southwest of Wagga.

The Munyabla fire was heading towards the township of Henty, between Albury and Wagga.

4.45pm Three people have been detained for questioning over the fire at Shalvey by local police. No charges have been laid.

4.34pm THE elderly and infirm are suffering in the heat with paramedics responding to more than 15 cases of heat exposure across Sydney since 2pm.

But a NSW Ambulance Service spokesman said the call outs for heat exposure were the "tip of the iceberg'' with paramedics responding to dozens of more cases resulting from "heat related illness'' including nausea, headaches, dizziness and loss of cohesion.

"We've definitely seen a rise in heat related illness and that goes hand in hand with a dramatic increase in heat exposure,'' he said.

"The interesting thing is most of our calls are not for heat exposure, they're for other heat related conditions such as nausea, headaches and that sort of thing which makes it almost impossible to quantify.''

The ACT Ambulance Service meanwhile has attended 19 cases from 7am to 3pm today for heat related conditions - 15 of which required transport to hospital - with patients aged between 14 years and 90.

Since 2pm NSW paramedics have responded to calls from Blacktown, Cronulla ``and everywhere in between'' with about 70 per cent of patients being described as elderly.

"We were seeing a slight increase in incidents this morning [but] as the temperature started to rocket up past 40 degrees about 2pm these incidents started rolling in,'' the NSW Ambulance spokesman said.

"More than 100 paramedic crews are operating across the metro Sydney area this afternoon.''

But the worst is not over with paramedics bracing for a second wave of heat-related calls after people finish work and start hitting the gym, going for runs or begin other evening team training sessions.

Paramedics have also renewed calls for people to check on their neighbours with the ``elderly, sick or infirm the most susceptible to heat-related conditions''

4.01pm There will be a state wide total fire ban again tomorrow. The fire danger will be further north in the state.

3.50pm Commissioner Mike Gallagher has praised the firefighters working to control blazes around the state:

"It is fair to say we have seen worsening conditions. The good news is that the expected wind change has brought temperatures from 40 down to 24 (in the south of the state). The bad news is it is moving slowly.

The thousands of firefighters are working incredibly hard as they go about this very dangerous job."

There are now 130 fires across the state and 40 of them are uncontained.

"It is very much a moving beast," RFS Commissioner Shane Fitzsimmons said.

"But they are being dealt with promptly and not being allowed to spread."

There are no reports of damaged or destroyed property.

Sussex Inlet in the Shoalhaven area is being warned to brace for dangerous conditions.

3.11pm: The record-breaking heatwave across most of central and southern Australia looks set to continue in the coming days, a climate expert warns.

Maximum temperatures across the continent in the last four months of 2012 were 1.6 degrees above average, breaking all previous records, the Bureau of Meteorology said today.

Aaron Coutts-Smith, the bureau's NSW manager for climate services, expects the run of dry and hot conditions to continue for at least the next week.

2.57pm: Flanked by fire on three sides, the Wagga Wagga horse races is set to complete its meet this afternoon despite the mercury reaching 40.8 degrees.

Murrimbidgee Turf Club CEO Scott Sanbrook said races were brought forward two hours so the majority of the eight-race card could be held before the hottest part of the day.

Mr Sanbrook said stewards were monitoring the heat and track conditions and the club had called in two additional veterinarians to ensure the horses' wellbeing were paramount.

The Gosford greyhounds are also set to go ahead tonight despite the heat with a "good breeze" keeping temperatures below the forecast 42 degrees.

Greyhound racing at Lismore in the state's far north east is also expected to go ahead from 6.50pm.

2.44pm: A fire is raging at Deans Gap near Nowra and has broken containment lines and is moving quickly. The fire is being tackled from the side due to its intensity. Main Road 92 has been closed between Braidwood and Nowra.

2.15pm: Reports of a firefighter hurt at Mates Gully near Wagga.

2.05pm: Ausgrid reported on Twitter that power was out for about 2100 homes and business in parts of Freshwater and Allambie Heights after a fault on overhead powerlines.

1.52pm: The Lockhart fire near Wagga is expected to reach the township of Henty in an hour.

It is now too late for the residents of Tarcutta near Wagga to leave. Southern properties are expected to be affected shortly and residents must seek shelter. The Hume Highway in the area is closed.

1.46pm: Two bridge climbers have been escorted off the Sydney Harbour Bridge with heat exhaustion in separate incidents during the extreme temperatures today.

In the latest incident, a teenage boy lost consciousness while climbing the bridge about 1.05pm.

He is currently being treated by paramedics.

In the Sydney CBD, the temperature was 40.9C when the teenage boy collapsed. A NSW Ambulance spokesman said heat had played a part in the incident.

"Like most jobs today, heat will be a factor," he said.

In the first incident, a teenage girl had to be brought down by BridgeClimb officials after she felt dizzy about 11.10am.

Paramedics treated the girl, who was conscious and walking, on the ground. She was not taken to hospital.

A BridgeClimb spokeswoman said it was just 32C on the bridge, which wasn't hot enough to cancel climbs."If at any time people at deemed at risk we would suspend operations immediately," she said.

The NSWRFS posted this image on Facebook with this cpation: This image is just in from our Line Scan aircraft, showing the Yarrabin fire in the Cooma area. The red and yellow sections show the most intense part of the fire, burning quickly through grassland.Source: Supplied

1.38pm:Journalist Ian Walker reports from RFS Headquarters: There's a small grass fire at Roach Rd Shalvey. It has multiple ignitions and has been deliberately lit. It isn't looking to be a threat.

1.35pm: Journalist Ian Walker reports from RFS Headquarters: As high temperatures and strong winds reach their peak this afternoon the Bureau of Meteorology has indicated the catastrophic fire danger is set to spread even further.

The areas affected include the Northern and Eastern Riverina and southern parts of the Lower Central West Plains.

The danger level is expected to remain for several hours ahead of a southerly change.

People are urged to avoid bushland areas and to have their bushfire survival plan in place.

These catastrophic areas are now in addition to the Illawarra/Shoalhaven and Southern Ranges.

There are currently more than 100 bush and grass fires burning across the state.

1.21pm:Journalist Ian Walker reports from RFS Headquarters: An emergency warning has been declared for Ryan's Rd at Munyabla in the Lockhart region.

The fire is moving quickly and is expected to impact on 10 isolated properties in 30 minutes. It is too late to leave and residents are urged to hunker down.

1.17pm: Sydney's temperature has hit 40C. Official records at the Bureau of Meteorology headquarters had the mercury at 40.4C at 1.05pm today.

Sydney Airport is also above 40C now, up at 40.8C.

Winds are expected to pick up from the west to 40km/h, increasing the temperature by a few more degrees by 4pm.

1.14pm: The fire near Cooma in the Kyeban Valley is now impacting 20 properties right up to their doorsteps. There is no possibility to leave. The affected area is between Tyban Rd, The Avenue, Haines Rd and Warnocks Rd.

1.11pm: A new fire has broken out at Tarcutta, 3km east of Wagga Wagga. RFS says it's likely to cut off the Hume Hwy.

12.54pm:Journalist Ian Walker reports from RFS Headquarters: Areas are moving to catastrophic conditions as the worst of the winds pick up.

Another major blaze has flared up on Moonbria Rd at the township of Jerildarie in the south west of the state. It may cut the Newell Highway.

The blaze near Cooma continues to spread putting out smoke and embers a kilometre in front of the fire in what is termed by firefighters as 'spotting'. A strike team has been sent to Nimitabel.

With 20 properties to be impacted it is too late for people to leave that area. When the fire front approaches residents must stay indoors to shelter from the radiant heat.

The fire near Bega is heading towards Warrigal Range Rd. Fire tricks are stationed at a number of properties and residents are still able to leave the area. The Princes Highway in the area is affected by smoke not fire.

12.49pm: Penrith is the first Sydney suburb to hit 40C. The mercury hit 40.2C at 12.30pm this afternoon.

Sydney CBD is close to hitting 40C as well, with temperatures at 12.30pm recorded at 38C at Observatory Hill.Richmond, Bankstown and Sydney Olympic Park were at 38.7C at the same time this afternoon.

Experts are predicting the temperatures to rise even higher over the next three hours.

12.45pm: A fire has broken out at the Lucas Heights nuclear research facility in Sydney's south. Fire and Rescue NSW Superintendent Tom Cooper said the call from the Australian Nuclear Science and Technology Organisation.

He told AAP the fire was in an electrical substation at the rear of the facility. The site contains two nuclear reactors.

Three fire crews and a hazardous materials crew were at the scene and two firefighters in breathing apparatus had entered an outbuilding to investigate, Supt Cooper said.

12.17pm:Journalist Ian Walker reports from RFS Headquarters: There is no sign of the heat abating at all today with temperatures of over 30 degrees expected to remain throughout the night.

"There's a lot of daylight and night time to go and a lot of heat left in this day. It's going to be a long hot day for communities and firefighters," RFS commissioner Shane Fitzsimmons said.

Heat, wind and dryness are three factors at play that can easily whip up and spread embers to unburnt country.

"Leaving early is the safest option for anybody in threatened areas," the commissioner has continued to remind people.

"This afternoon will be particularly problematic."

12.05pm: An emergency warning has been issued for Warrigal Range in Bega. People are being asked to leave now if the path is clear and to relocate to Bega.

11.46am: Tony Abbott is on standby with his local fire brigade as NSW nervously awaits the outbreak of new bushfires.

"I'm now on my way to Sydney to be on standby with my local fire brigade," Mr Abbott tweeted."Important to follow fire warnings and advice today."

11.43am: Taronga Zoo keepers are handing out frozen treats to help its residents keep cool. Zebras will lick on icicles made of frozen carrot puree while lions snack on milk ice blocks.

"We will be giving them a variety of cold enrichments to make their day interesting and give them an opportunity to cool down,'' said the Zoo's behavioural biologist, Dr Vicky Melfi.

11.18am: There is a serious blaze in the Brogo area near Bega. People east of Warrigal Range Rd and west of Eagle's Nest Rd are advised if the path is clear to head towards Bega. It will impact isolated rural properties near Brogo in half an hour.

10.54am: Fire has jumped Numeralla River. People in Kybean Valley have been told by the RFS to "leave now and head to Nimmitabel."

10.24am: A grass fire 14km east of Wagga which has been raging since yesterday has breached and aircraft have been deployed to help battle it.

10.04am: In Bega, on the NSW south coast, temperatures rose nearly 20C in just three hours this morning. The city reached 39C at 9am after an overnight low of 15.4C at 6am.

9.58am: People in the NSW town of Carlaminda have been told to get out or take cover as an out-of-control fire bears down on them.

9.47am: Sydney's outer suburbs are already feeling the heat - with parts of the west sweltering in temperatures above 30C at just 9am this morning.

According to official temperatures at the Bureau of Meteorology headquarters, the mercury was highest at Richmond (34.2C), Terrey Hills (32.2C), Penrith (31.9C) and Canterbury (30.8C).

Lake Macquarie recorded the highest temperature for the surrounding Sydney region with 33C at 9am.

At Sydney's Observatory Hill, where the CBD temperature is officially measured, the mercury had risen to 28.2C by 9am.

Temperatures are still predicted to climb by more than 15C in some parts of Sydney before 3pm today.

9.41am: Journalist Ian Walker reports from RFS Headquarters: Greg Mullins, Fire and Rescue NSW Commissioner, who is leading the urban recovery has directed all people seeking information on the fires to the "point of truth" at the RFS website.

"Between us and the RFS it's a seamless operation. It doesn't matter what colour the trucks are it will be dictated from here," Mr. Mullins said.

"In my 40 years I haven't seen conditions this bad. I couldn't sleep last night and I have a terrible feeling in the pit of my stomach. It's been 19 years to the day since we lost homes in northern and southern Sydney."

This anniversary has served as a significant warning and reminder to people in urban areas, particularly in Sydney, to not be complacent.

"The stay or go decision is not to be made when a fire is bearing down on your house," Mr. Mullins said.

"We're going to hit them hard. We know some of these fires are going to be big ones. We usually send one truck to grass and bush fires but today we will be sending two and depending on the amount of triple zero calls we get we'll send a helicopter."

There are 2100 RFS fire trucks dotted in areas across the state.

Fire and Rescue NSW has 400 "strike teams" in its urban range with 50 extra trucks on reserve.

9.33am: Almost 40 per cent of Australians do not have a fire escape plan and many are not taking basic precautions to protect their homes against bushfires.

According to new research by GIO, only three in five people - or 58 per cent - know what to do if a bushfire threatened their home.

9.22am: Wollondilly shire, south of Campbelltown, has joined the Illawarra, Shoalhaven and Southern Ranges on catastrophic bush fire alert, the Macarthur Chronicle reports.

Residents in many shire towns, including Wilton, were sent an emergency alert telephone warning message last night, about today's catastrophic conditions.

Residents were urged to think about when they would leave, where they would go and how they would get there, should a fire break out nearby.

9.17am: A fire in the Monaro area in Carlaminda has broken containment lines. SMS communication has been sent and people are urged to be out within twenty minutes

9.02am: Journalist Ian Walker reports from RFS Headquarters: Firies from across the state are checking in at the RFS Headquarters waiting for their instructions.

The commissioner Shane Fitzsimmons has indicated the tough day that lies ahead for them all.

"Conditions are shaping up as predicted. We're already seeing hot temperatures as places like the Shoalhaven, Illawarra and Southern Ranges are climbing into the 30s," he said.

Those outside of the catastrophic area are urged to be vigilant.

"The geography is widespread. We can't lose track of vast areas of NSW so we will need people to stay alert and informed and use radio, tv and social media.

"When I was a kid we'd be outside but these days people bunker down with their home entertainment.

"You can't be disconnected today. We need the community to ring 000 if they see anything. Fire behaviour will be at its most extreme and if we can get there early we have our best chance," the commissioner said.

8.40am: Prime Minister Julia Gillard has warned Australians to keep safe as a day of extreme fire danger unfolds around the nation.

Tasmania continues to burn, Victoria faces a renewed fire threat and NSW will today wake to its most dangerous fire-risk day on record.

"We of course are very concerned about these extreme weather conditions in NSW. The word catastrophic is being used for good reason," she told the Seven Network this morning.

8.33am: The Salvation Army are also on standby to assist emergency services across the state of NSW if required.

There are 87 teams on standby in NSW and ACT, and all are in a position of readiness to swing into action.

The Sallies advise people to follow directions provided by authorities about protection from hot weather and fire dangers, as well as to pay particular attention to elderly relatives who are living alone and those suffering sickness at this time.

7.00am: All national parks and reserves across NSW will be closed today due to the extreme risk of a bushfire.

As the mercury began its steady climb this morning, there were 100 fires burning in NSW, 21 of these fires were uncontained, said NSW Rural Fire Service Commissioner Shane Fitzsimmons.

"Fortunately none of these fires are posing any immediate threat," he said. "But clearly, under today's conditions, we are concerned with those and we will be monitoring them very carefully."

More than 1500 firefighters worked overnight to control the blazes.

There it a total fire ban on the entire state with temperatures in the state's far west predicted to hit 45 degrees, while in Sydney the mercury is forecast to climb to 43 degrees - making it the third highest temperature on record.

People living in Shoalhaven, the Illawarra and the southern ranges face the most risk.

"We are shaping up for one of the worst fire danger days on record," Comm Fitzsimmons said this morning.You don't get conditions worse than this, we are at the catastrophic level and clearly in those areas leaving early is your safest option."

Overnight more than a million people were called by telephone or by SMS to reinforce the leave early message.

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